[unreadable] Efforts to establish MRI guided intervention as clinically practical are hampered by a lack instruments that are safe and exhibit clinically useful MRI visibility. We propose to introduce and develop an advanced class of microcapsule (mCAP) contrast additives optimized for use with medical grade polymers, mCAP enhanced polymers will allow MRI compliant instruments exhibit clinically relevant MRI visibility while retaining existing mechanical and manufacture properties. Although the proposed enabling technology is applicable to many devices, this grant application focuses primarily upon developing MR-visible vascular catheters. This will be accomplished by: [unreadable] [unreadable] 1) Identifying base materials and encapsulation procedures to: establish feasibility and set performance baseline. [unreadable] 2) Explore variations in material formulations and polymer processing to: [unreadable] a) Demonstrate ability to optimize performance. [unreadable] b) Identify paths for in depth Phase II development. [unreadable] 3) Lastly, three (3) different prototypes devices are constructed and tested to demonstrate: [unreadable] a) mCAP compatibility with a range of polymers. [unreadable] b) Direct MR visibility with contemporary MR imaging sequences. [unreadable] [unreadable] Mechanical properties and image performance are quantified for each prototype. Results are compared with quantitative criteria to establish proof-of-concept. If successful, mCAP enhanced polymers should enjoy broad applicability and contribute to the adoption of minimally invasive, MRI guided interventions. [unreadable] [unreadable]